1. Field of the Invention
This invention relates to a print head type face inking device for use in a label printing and applying machine, or the like machine. The inking device applies ink evenly so as to attain precise printing of labels.
2. Description of the Prior Art
In conventional label printing and applying machines and tag printing and attaching machines, devices for applying ink to the type faces of the printing heads usually comprise inking rollers that are attached to the free ends of spring-actuated rocking arms. The inking rollers are pressed to and rolled over the type faces so as to apply the ink.
A typical inking device of this type comprises a pair of spring-actuated rocking arms attached to the front end portion of the printing machine body. A supporting frame carrying an inking roller is attached to the rocking arms through springs. When the hand lever of the printing machine is squeezed, the rocking arms are turned simultaneously, and this moves the inking roller supporting frame. Thus, the inking roller is rolled over the type faces of the printing head. This conventional inking device has a number of disadvantages:
(a) Since the inking roller is brought into contact with the type faces by spring action, ink application is liable to deteriorate when the force of the spring becomes weakened after long use of the machine. Therefore, the printing of labels becomes indistinct, which is fatal to optical character reading systems requiring highly precise printing. PA1 (b) When the inking roller spring force becomes weak, only the ink contained in the portion near the surface of the inking roller is used, because the type faces no longer dig deeply into the inking roller and the ink that is impregnated in the middle portion of the inking roller is not pumped out. Therefore, the printing of numerous labels is impossible, which is uneconomical. PA1 (c) When the hand lever of the printing machine is squeezed quickly, the inking roller sometimes makes slight contact or no contact with type faces due to the rebounding action caused by the squeeze. Thus, reliable printing cannot be expected. PA1 (d) Strong force is necessary to operate such label printing machine, so that some operators, like the weaker ones, are tired by long term handling of a machine. PA1 (e) In the conventional label printing machine, the rocking arms, supporting frame and inking roller are moved forwardly through the front part of the printing machine when the hand lever is fully squeezed until they protrude in front of the machine frame. The protruding parts obstruct the operator's view as the just printed label is being applied to the surface of an article, and accurate application of the label becomes difficult.